The present invention relates to an electric connection box for protecting a junction block provided to an engine room, etc. of a car against water.
In general, an electric connection box accommodates a junction block equipped with electric parts such as a fuse, a relay and a connector in an inner space which is opened on a lower cover, and the opening of the lower cover is closed with an upper cover (see Japanese Unexamined Utility Model Laid-Open No. 1-58983). A packing is fixed to at least one of fitting portions of the upper cover and the lower cover. When the upper cover is fitted so as to cover the lower cover with the packing being sandwiched between the fitting portions, the packing is pressed, and thus water tightness between the fitting portions is improved. As a result, the junction block in the electric connection box is protected against water.
In such an electric connection box, after the junction block is installed to the lower cover, in order to connect harnesses below the junction block in the inner space, it is necessary to cut an opening on one basal side wall of the lower cover from an upper edge to a bottom side. In the case such an opening is formed, in order to obtain the above waterproof effect which is same as the case where the opening is not formed, a side wall which closes the opening is formed on the upper cover, and a packing is fixed to at least one of the fitting portions between the upper cover including the side wall and the lower cover including the opening.
However, if the opening of the lower cover and the side wall of the upper cover have a square shape whose right and left edges are approximately parallel with each other, when the upper cover is put on the lower cover from above, the right and left edges of the side wall are slid along the right and left edges of the opening, and thus the packing is pressed. As a result, the following problem arises. Namely, because of scattering in a dimension within a tolerance range of the manufacturing of the lower cover and the upper cover, when a width of the opening is too larger than a width of the side wall, for example, the packing between the right and left edges of the opening and the side wall is not sufficiently pressed, and thus satisfactory waterproofing is not obtained. On the contrary, when the width of the opening is too smaller than the width of the side wall, the packing between the right and left edges of the opening and the side wall is pressed excessively, and thus the fitting becomes difficult.